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Discussion Starter · #1 ·
I've read on here a few times that our a/c is a sealed system and that if we need to add some refrigerant because we're blowing warm air it's most probably due to a leak somewhere.

Is this the case for every car or do we need to add every couple of years because we use up the refigerant?
 

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It does seem like some cars just naturally eat up a little freon over the years. My '02 ZX3 was blowing "cool" but not cold air, so I added a small amount and now it's ice cold again. If the system does have a leak then you should get it fixed otherwise you'll just be throwing money away. But if every few years you have to top it off with just a touch of freon then I don't think that's a big deal.
 

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"It does seem like some cars just naturally eat up a little freon over the years."

Yeah, it is tough to keep an A/C system completely sealed, particularly with the complexity of installation in a car. Theoreticaly speaking, there should be no loss. (my Home A/C is 15 years old and still operating normally, and it is not unusual for home refrigerator systems to go 10-15 years with zero leakage). Practically speaking, few car systems are sealed so perfectly that they do not have some small leakage, such that after a few years a "top off" is required. I suspect it has to do with the fact that automotive systems tend to have more connectors relying on O-rings and threaded fittings, and also endure a lot more vibration, while the home and refrigerator A/C systems are not subject to vibration and also rely more upon soldered connectors.
 

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according to IMACA, the acceptable amount of leakage for mobil air conditioning systems is .25 ounces of freon per year. since your car holds about 28 or so ounces, it would take about a century or so to lose all your freon due to 'normal leakage'

You have a leak
 

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1) An A/C system doesn't have to lose all of it's charge to stop working -- the low pressure sensor will stop the A/C when the refrigerant gets low. I am not sure about the news R134A systems, but on my old Ford Explorer, losing 1/4 of the total charge was enough to stop the compressor from kicking on for more than 2 seconds at a time.

2) Of course he has a leak. That said, if the leak is quite slow, it may be more practical and cost effective to simply top up the refrigerant every 3-4 years as compared to the cost of tracking down the leak, fixing it, vacuum purging the system, and then totally recharging the system. On a four year old vehicle, I would try a recharge with some leak detector first. That might be good enough to get another 3-4 years, and if not, the leak detector would help find the leak.
 

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A/C system are not 100% sealed! there are always loss of gasses. Mostly though the flexible hoses. The gasses pass threw the hoses, by seeping. This is very slow and is normal. O rings and fitting are another way. The compressor also loses a bit via the seals. So even if all is sound and tight, we all still need top ups, it normal. But if you lose your gas with in a year you got a big leak.


www.bluewhippet.net
 

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What the F does bluewhippet have to do with A/C?

All AC systems are sealed, not just the Focus. None should lose gas. As said, it's possible to have a tiny leak. And if you only need a top off once every couple years should you tear in? No way. But anything more and your throwing money away, fix it.
 

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downloader said:
A/C system are not 100% sealed! there are always loss of gasses. Mostly though the flexible hoses. The gasses pass threw the hoses, by seeping. This is very slow and is normal. O rings and fitting are another way. The compressor also loses a bit via the seals. So even if all is sound and tight, we all still need top ups, it normal. But if you lose your gas with in a year you got a big leak.


www.bluewhippet.net
And all the examples you list should amount to only .25 oz per year, or it is considered excessive.

For example, my 1993 Ford Ranger still blows 36 degrees from the vents, it has never been serviced or 'topped off' in its life. That's a nearly 14 year old truck with 220,000 miles on it. I would be willing to wager, it doesn't have any excessive leaks.

My 2002 Ford Explorer needed a 'top off' last summer, so I installed some ultraviolet tracer dye along with the freon. Sure enough, 6 months later, it was still blowing fairly cold, but when I shined the UV light on the system, I found a leak at the compressor discharge hose. Excessive leak. (lost 6oz in 6 months)

If you are losing enough to shut off your compressor, that's well over a pound of freon gone (usually down to a 1/3rd of capacity when a/c wont come on anymore)



Some will say "so what? Freon's cheap, why can't I just keep adding it?" Here's why..

Your a/c compressor has basically the same components as your engine. Valves, pistons and rods, even a 'crank' of a sort. It also has an oiling system. You change the oil in your motor every 3000 miles right?
You never change the oil or even check it in your compressor.. So when you have a leak in the system, you have three problems.

The first problem is obviously you are losing the freon in the system.

The second problem is you losing the OIL in the system, and what's left is getting attacked by the contaminants caused by the leak.

The third problem is you are letting MOISTURE into the system. (regular air + freon = hydrochloric acid, in case you weren't aware)

Problems 2 and 3 are hidden for a while, until suddenly you have a $1000.00 repair bill because your compressor ran low on oil and seized or the level of acid in the system has raised enough to destroy the condenser, evaporator, compressor piston rings etc...

So you see, all the guys who advise you to 'do it yourself and save' 'don't know about the long term effects of putting a 'band-aid' on your a/c system. Sure you can get away with 'topping it off' for a while... until it blows up in your face.
 

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Discussion Starter · #9 ·
Very nice info guys! Thanks for replying.
 

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"you are letting MOISTURE into the system."

Considering the pressure the system is under, even at "rest," it is rather difficult to see how moisture is getting into the system against the pressure gradient.
 

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You are not letting moisture into a leaking system until it is at zero pressure and even then it is very difficult to get any water contamination unless you open the system.(take off a component)There is at least 8 oz. of compressor oil in most systems and is not as transient as refrigerant.(oil stays put in the system,even if it's leaking) If you need to "top off" your system every year or less,you have a gross leak and a problem.If you "top off" your system and overdo it,which is easily done unless you add only the specific weight charge to the system,you will RUIN your compressor.It cannot compress liquid refrigerant,which is what you will have if the system is overcharged.Kind of like hydrostatically locking your motor with water through a poorly designed CAI.One more thing;NO Focus ever came with Freon.They use R134a,like most 1994 and newer cars.
 

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seeing as how most folks don't address their a/c problems until the REFRIGERANT level is near zero anyway, it is very easy to let normal air into the system. Normal air contains MOISTURE. The higher the humidity in your area, the more moisture it contains.

You don't have to 'leave the system open" to get moisture into the system, it occurs anyway. It just accelerates with a leaking system. Your accumulator contains a dessicant to help absorb that moisture, but it can only handle so much.

I'm not trying to say you can't top off, I'm just saying if you are doing it once a year, you are risking a big bill in the future. Instead of the "top-it and forget-it" approach, spend the extra few bucks, install a tracer dye with the refrigerant and the next time you have a problem, you can easily find it with a UV light.

I have no idea why folks seem to want to convince other people to ignore the warning signs of a problem. Thats like telling a guy to just keep topping off his oil and ignore the fact that he loses a quart every other month. "Spare no concern as to where its going or why, heck its just oil!" Til the rod bearing seizes, or the cat clogs and blows out.
 

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"seeing as how most folks don't address their a/c problems until the REFRIGERANT level is near zero anyway,"

I find most people address it when it quits working, which, as you agree, is when only about 1/4 - 1/3 of the refrigerant is gone.

"I have no idea why folks seem to want to convince other people to ignore the warning signs of a problem."

People are not doing this, at least I'm not. We just are trying to save the guy a few buck based on real World experience. As I said earlier:

"Of course he has a leak. That said, if the leak is quite slow, it may be more practical and cost effective to simply top up the refrigerant every 3-4 years as compared to the cost of tracking down the leak, fixing it, vacuum purging the system, and then totally recharging the system. On a four year old vehicle, I would try a recharge with some leak detector first. That might be good enough to get another 3-4 years, and if not, the leak detector would help find the leak."
 
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